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TDU Microwave/Telsa prize

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vasil

Fri Sept 01 2006, 08:32PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

TDU, are you thinking to a flat secondary, glued on the glass plate with the primary beneath?

Oh, and for the cap you have to get out from the metalic case (you will be dirty from the oil). Just use enough paper-foil combo to have a few nF cap for the primary tank.

...and you can still increase the input voltage if you rectify it. Just use the magnetron, without the permanent magnets, as a HV diode. It will keep well with the HF spikes (far better than the silicon diode). And you can ballast the MOT just decreasing the fillament current (lower the fillament turns number)

Tesladownunder

Sat Sept 02 2006, 02:53AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

vasil wrote ...

TDU, are you thinking .....
..Just use enough paper-foil combo to have a few nF cap for the primary tank.

...and you can still increase the input voltage if you rectify it. Just use the magnetron, without the permanent magnets, as a HV diode. It will keep well with the HF spikes (far better than the silicon diode). And you can ballast the MOT just decreasing the fillament current (lower the fillament turns number)

If I told you what I was thinking, I'd have to kill you of course.

Paper-foil? Paper from where? Perhaps from the circuit diagram that some older MO's had pasted to the chassis lid.

The magnetron/diode idea is interesting and makes me wonder if you can't arrange a two stage CW multiplier rather than just a single. That would be really clever.

After the next reply I will show a pic of my progress.

Peter

vasil

Sat Sept 02 2006, 05:43AM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

Ok, my mistake, wrong word. I mean mylar - foil, what you find inside the MO cap.

Unfortunately I only can play with ideas. No MWOs to distroy around....just a few separate parts.

Tesladownunder

Sat Sept 02 2006, 05:59AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Vasil has exposed my secret about the caps. Damn

Here is a high voltage test of my former. I should have done this before I started the winding. Seems that it doesnt conduct at least.

Can you see where I got the former from? Yes it is out of the MO.

Peter

1157176793 10 FT15477 Moteslaprizesecformertest

vasil

Sat Sept 02 2006, 06:14AM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

Is it the piece of plastic that covers (and protect) the microwave window (between magnetron and oven)? I saw something like that in a few ovens.

Tesladownunder

Sat Sept 02 2006, 06:25AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

That is a reconstituted mica window. Almost all MO's seem to use them. Nice and heat resistant and I used a stack of 4 or more for the base of a static gap on a Tesla coil I made recently for the Physics Dept. PVC was getting too hot with the 110 mA NST. They are easy to miss but can be pried out by approaching from the cooking cavity side being careful not to crack them.
A useful part for this project, no doubt but not what I used.

Peter

Nik

Sun Sept 03 2006, 02:26AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I found a MWO put out on the side of the road because there was a peice of metalized cardboard where that mica sheet usualy is. THe thing had caught on fire and the owner threw it out it would seem.

Tesladownunder

Sun Sept 03 2006, 08:27AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Here are a couple of progress photos.

The display board usually has a small mains transformer on it which can be unwound and has 43 M of wire on the smaller winding. The larger winding with smaller wire should be much longer but it wouldnt break through the lacquer and snapped.

The secondary is being wound fronm the fan motor wire.

Peter

1157272058 10 FT15477 Hvmotesladisplaytransformerwire

1157272058 10 FT15477 Hvmoteslafanwiresecondary

Michael W.

Sun Sept 03 2006, 01:41PM

Registered Member #50 Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324

I'm not participating but heres a coil I wound from a microwave fan motor. It measures 4"X1", not sure of the gauge. I didn't even break the wire once, winding by hand.

ragnar

Sun Sept 03 2006, 09:58PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

You could probably cut slots into those fanblades to assemble them into an BP-memorial "anticoil" of some description... although if it ends up with a conical shape, the wire will just slide off... Low-loss, though =)

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